The present invention generally relates to a storage system and a data guarantee method, and, for instance, can be suitably applied to a storage system using inexpensive hard disk drives.
In recent years, pursuant to the development of information society, the volume of data from a host system to be stored in a storage apparatus is increasing rapidly, and the storage capacity in a storage apparatus is being enlarged according to such rapid increase. Thus, in a storage apparatus, a disk array configured from RAID (Redundant Array of Independent/inexpensive Disks) is foremost created from hard disk drives, and a plurality of such physical storage resources are gathered to create a physical volume in order to seek the enlargement of the storage capacity in the storage apparatus.
As the hard disk drives supporting the foregoing RAID configuration, there are expensive hard disk drives having high performance and high reliability of data, and inexpensive hard disk drives capable of storing large capacity data but unable to guarantee the reliability of data.
These hard disk drives are used appropriately in consideration of the quality and volume of data to be stored in the storage apparatus, customer needs, and other factors.
Particularly in recent years, demands for storing data with the heavy use of inexpensive hard disk drives are increasing.
As primary technology for increasing the reliability of data to be stored in inexpensive hard disk drives, there is the method disclosed in Japanese Patent Laid-Open Publication No. 2006-251960. Japanese Patent Laid-Open Publication No. 2006-251960 proposes a method of guaranteeing the reliability of data by creating compressed data of host data, and comparing the compressed data and data to be stored in a storage extent that is different from the storage extent to which such compressed data is to be stored.